The present invention relates to an art of sticking a thin film, and particularly relates to an effective art of sticking a thin film to the surface of a base plate.
In a printed circuit board for an electronic machine such as a computer, wirings of copper or the like are provided in a prescribed pattern on one or both sides of an electrically insulating base plate. The printed circuit board is manufactured in a process described from now on. A stratified body consisting of a photosensitive resin layer and a light-transmissible resin film for protecting the layer is first stuck, under heat and pressure, to an electroconductive layer provided on the electrically insulating base plate and made of a thin copper film. The heat and pressure sticking is preformed by a thin film sticking apparatus in a mass production manner. A wiring pattern film is then over laid on the stratified body. The photosensitive resin layer is exposed to light through the wiring pattern film and the light-transmissible resin film for a prescribed time. After the light-transmissible resin film is peeled from the stratified body by a peeling apparatus, the photosensitive resin layer exposed to the light is developed so that an etching mask pattern is made. After that, the unnecessary portion of the electroconductive layer is removed by etching, and the remaining portion of the photosensitive resin layer is then removed The printed circuit board having the prescribed wiring pattern is thus manufactured.
Since the surface of the above-mentioned electroconductive layer has minute recesses and projections, air is left in the recesses when the stratified body is stuck to the surface of the layer. For that reason, air bubbles are generated between the mutually stuck surfaces of the electroconductive layer and the stratified body to decrease the adhesive power between them to lower the reliability of the wirings of the printed circuit board.